The purpose of the proposed work is to study the physico-chemical aspects of the processes involved in demineralization and remineralization of dental enamel. Special emphasis will be given to the properties of the tooth-saliva interface. Under natural conditions, part of this interface is the acquired tooth pellicle which forms through a selective adsorption of salivary glycoproteins and peptides. The proposed work encompasses studies on adsorption of purified salivary components to ascertain the way in which the acquired pellicle is built up. The properties of these pellicles will be studied particularly in relation to transport phenomena (e.g. ionic permselectivity) and their effects upon demineralization by acid buffers and cariogenic microorganisms. Studies are also proposed to ascertain the factors controlling enamel remineralization. In this connection, experiments will be conducted to determine the rate of crystal growth of calcium apatites in the presence of salivary components. The results of these experiments will be applied to the study of enamel remineralization in vitro.